Deadly combination can turn celebration into horror

Top News | Sophie Hui and Stella Wong 23 Nov 2018

A dust explosion is the rapid combustion of fine particles suspended in the air, a chemistry professor said.

Jason Chan Kwan-kit, a Hong Kong University of Science and Technology lecturer in the Department of Chemistry, said while flour itself is not flammable, it can become combustible once it spreads in the air.

"Flour is a combustible substance, but it can't be burnt or is difficult to burn when it is not blown," he said. "When it is spreads into the air, there is a big surface area of flour particles, and it will have a chemical reaction with oxygen quickly.

"If there is kindling material, it can burn in a short time and create a large fire."

Besides flour, Chan said other powders, including corn starch, cocoa powder and plastic powder, can become flammable and explode when it spreads in the air.

The professor conducted an experiment blowing powder toward a fire gun. In just two seconds, the flame flared to a height of about a meter.

He said people should raise their awareness.

"It is not possible to react in time because the dust explosion occurs in a fraction of a second. The best way is to prevent it from occurring," he said.

A similar dust explosion happened in Taiwan in June 2015, killing 15 people and injuring about 500 at a party. Six of the injured were Hongkongers.

During a "Color Play Asia" concert at a water park in New Taipei City, a huge amount of colored corn starch powder was thrown onto 1,000 people.

When a cloud of powder fell onto the surface of the stage light, it suddenly exploded and a huge fireball engulfed the stage.

Some people breathed in the powder, causing them serious respiratory injuries.

On the same day, Taiwanese authorities banned all recreational activities involving dust powder.

Hong Kong also canceled activities involving colored powder that year, including The Color Run and Life in Color.

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